Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2017
Authors
Patryk Czortek Jutta Kapfer Halina Ratynska Amy Eycott Anna Delimat Antoni Zieba Anna Orczewska John-Arvid Grytnes Bogdan JaroszewiczAbstract
No abstract has been registered
Abstract
Habitat loss is one of the primary environmental causes of biodiversity decline across scales; locally to globally. Ecological restoration is acknowledged as an important tool to counteract this negative trend. The semi-natural calcareous sand dune meadows in south-western Norway are known for their high species diversity, much like similar habitats of high conservation value across Europe today. The recent cessation of grazing has caused a decline in several endangered species associated with these habitats due to the advancement of secondary succession. We conducted a long-term restoration experiment in semi-natural dune meadows over 16 years to examine if current trends in biodiversity loss could be reversed and at what time-scale restoration measures take effect. Three treatments were applied; mowing annually, mowing bi-annually, and a control (no mowing). In fields mown annually species richness increased significantly over time. However, the response was slow and significant effects were first seen after year 10. Fields mown bi-annually also showed a similar trend but the response was more variable. Several characteristic meadow species were favoured by annual mowing while they declined in the control fields. Principal component analysis (PCA) revealed a compositional shift, indicating the re-arrangement/-establishment of typical meadow vegetation in the mown sites, contrasting the further successional development in the control. Our results demonstrate the importance of long-term data in supporting good evidence-based management. Annual mowing is effectively restoring this unique habitat, but restoration efforts need to be sustained over many years to show positive effects.
Abstract
The composition of plant secondary metabolites (PSMs) extensively impacts ecosystem functioning. It is vital that we understand temporal patterns in the plants’ allocation of resources to PSMs, particularly those influenced by human activity. Existing data are insufficient in the long-term perspective of perennial plants (age or ontogeny). We analysed phenolic concentrations in foliage from birch (Betula pubescens Ehr.) considered to be undamaged and growing on 5, 10 and 15 years old clear-cuts in two boreal forest landscapes in Norway, sampled at the peak of the growing season. In sum, low molecular weight phenolic concentrations decreased with age. Apart from one apigenin glycoside, the low molecular weight phenolics co-varied similarly at all ages, suggesting a lack of temporal compound-specific prioritisation of this group. In contrast, the concentration of MeOH-soluble condensed tannins increased with age. The compositional shift fits well with several hypotheses that may provide proximate explanations for age patterns in PSM allocations, including both resource constraints and external pressures. Regardless of these explanations, our study adds an important perennial perspective (plant age) to temporal PSM patterns already well-known in boreal plant phenology (foliage age).
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Plant defence against environmental stressors often changes dramatically as plant develop. The composition of secondary compounds (PSM) in the vegetation of a landscape has extensive influence on ecosystem functioning. It is therefore crucial that we understand how various temporal factors affect plant content of PSMs, particularly those indirectly induced and controlled by human activity. One illustrative PSM group of major ecological interest is phenolics, which serve needs as diverse as herbivory defence, pathogen resistance, allelopathy or symbioses signalling, frost and drought hardiness, and photodamage protection. I will present results from our ongoing studies of defensive chemistry of European beech (Fagus sylvatica) and birch (Betula spp) across seasons and ages, and discuss the results in relation to ecological theories and functionality of plant chemical defence.
Abstract
Despite decades of intense research, it remains largely unsolved which nutritional factors underpin food selection by large herbivores in the wild. We measured nutritional composition of birch foliage (Betula pubescens) available to, and used by, moose (Alces alces) in natural settings in two neighboring regions with contrasting animal body mass. This readily available food source is a staple food item in the diet of moose in the high-fitness region, but apparently underutilized by moose in the low-fitness region. Available birch foliage in the two regions had similar concentrations of macronutrients (crude protein [CP], fiber fractions, and water-soluble carbohydrates [WSC]), although a notably lower variation of WSC in the low-fitness region. For minerals, there were several area differences: available birch foliage in the low-fitness region had less Mg (depending on year) and P, but more Ca, Zn, Cu, and Mn. It also had higher concentrations of some plant secondary metabolites: chlorogenic acids, quercetins, and especially MeOH-soluble condensed tannins. Despite the area differences in available foliage, we found the same nutritional composition of birch foliage used in the two regions. Compared to available birch foliage, moose consistently used birch foliage with more CP, more structural fiber (mainly hemicellulose), less WSC, higher concentrations of several minerals (Ca, Zn, K, Mn, Cu), and lower concentrations of some secondary metabolites (most importantly, MeOH-soluble condensed tannins). Our study conceptually supports the nutrient-balancing hypothesis for a large herbivore: within a given temporal frame, moose select for plant material that matches a specific nutritional composition. As our data illustrate, different moose populations may select for the same composition even when the nutritional composition available in a given food source varies between their living areas. Such fastidiousness limits the proportion of available food that is acceptable to the animal and has bearings on our understanding and application of the concept of carrying capacity.
Abstract
Tick-borne fever (TBF) is stated as one of the main disease challenges in Norwegian sheep farming during the grazing season. TBF is caused by the bacterium Anaplasma phagocytophilum that is transmitted by the tick Ixodes ricinus. A sustainable strategy to control tick-infestation is to breed for genetically robust animals. In order to use selection to genetically improve traits we need reliable estimates of genetic parameters. The standard procedures for estimating variance components assume a Gaussian distribution of the data. However, tick-count data is a discrete variable and, thus, standard procedures using linear models may not be appropriate. Thus, the objectives of this study were twofold: 1) to compare four alternative non-linear models: Poisson, negative binomial, zero-inflated Poisson and zero-inflated negative binomial based on their goodness of fit for quantifying genetic variation, as well as heritability for tick-count and 2) to investigate potential response to selection against tick-count based on truncation selection given the estimated genetic parameters from the best fit model. Our results showed that zero-inflated Poisson was the most parsimonious model for the analysis of tick count data. The resulting estimates of variance components and high heritability (0.32) led us to conclude that genetic determinism is relevant on tick count. A reduction of the breeding values for tick-count by one sire-dam genetic standard deviation on the liability scale will reduce the number of tick counts below an average of 1. An appropriate breeding scheme could control tick-count and, as a consequence, probably reduce TBF in sheep.
Authors
Gunnar Austrheim Victoria Berger Marc Daverdin Winta Berhie Gebreyohanis Anders Lorentzen Kolstad James David Mervyn Speed Aurel M A Venete Stein Joar Hegland Erling Meisingset Atle Mysterud Erling Johan SolbergAbstract
No abstract has been registered